Three-dimensional electroluminescence display

ABSTRACT

The three-dimensional electroluminescence display comprises a main body ( 1 ) and an electroluminescence device ( 20 ). Said electroluminescence device ( 20 ) comprises a film ( 2 ) and an electroluminescent arrangement ( 10 ) which together form a whole. The surface of the film ( 2 ), facing the electroluminescent arrangement ( 10 ) is provided with the motifs ( 9 ) for display. The electroluminescent arrangement ( 10 ) comprises a front electrode ( 11 ) and a back electrode ( 12 ), between which a dielectric ( 13 ) is located. The front electrode ( 11 ) is provided with the layer which produces the motif ( 9 ) and is embodied in one piece with the same. A supply source ( 15 ) is arranged within the surface of the electroluminescence device ( 20 ), which contacts the electrodes ( 11,12 ) of the electroluminescence device ( 20 ).

The present invention relates to a three-dimensional electroluminescentdisplay having a transparent front part and having an electroluminescentapparatus arranged behind said front part.

A three-dimensional electroluminescent display of this generic type isalready known. This previously known unit has a transparent sheet. Byway of example, the front large area of said sheet is provided with alayer which is not light-transmissive and in which motifs, such as e.g.graphics, symbols, images or the like, may be embodied. In order toprotect these motifs, the front side of the motif is covered with aprotective layer made, for example, of a clear and hard resin. Anelectroluminescent apparatus or an EL lamp is assigned to that side ofthe sheet which is remote from the motif. Said EL lamp is provided withstraps or lugs, of which one lug is connected to one of the electrodesof the EL lamp and the other lug is connected to the other electrode ofthe EL lamp. The EL lamp is supplied with electrical energy via saidlugs or straps.

The front region of this previously known unit is of complicatedconstruction owing to the need to use a plurality of layers. Moreover,it is often demanded that the display units have a non-planar form. Thisis because it is often demanded that the display shall have windows ordepressions whose side areas shall likewise luminesce. For this purpose,the EL lamp has to be drawn from the front area of the display rightinto the region of the side walls thereof bounding said window or saiddepression. Inter alia owing to the layer construction which tendstoward cracking in the previously known display, the latter can only bebent gently. The minimum achievable radius of a curved portion of thepreviously known display is in the region of about 6 mm. This is aradius that is too large for example in panel units in an automobile.The fitting of the abovementioned straps or lugs to the electrodes ofthe EL lamp is also problematic. This is because said electrodes areformed by very thin layers, while the straps or lugs are comparativelythick material strips in comparison with the electrode layers.

The object of the present invention is to eliminate these and alsofurther disadvantages of the prior art.

In the case of the three-dimensional electroluminescent display of thegeneric type mentioned in the introduction, this object is achievedaccording to the invention in the manner defined in the characterizingpart of patent claim 1.

Embodiments of the present invention are explained in more detail belowwith reference to the accompanying drawings, in which:

FIG. 1 shows a plan view of the front side of one of the embodiments ofthe present three-dimensional electroluminescent display,

FIG. 2 shows a vertical section through the structural part from FIG. 1,

FIG. 3 shows a section through a detail from a semifinished product, thefurther processing of which leads to the display unit from FIG. 1,

FIG. 4 shows a section through the semifinished product of FIG. 3 aftersaid product has been subjected to a thermoforming treatment,

FIG. 5 shows a section through the semifinished product of FIG. 4 aftersaid product has had a suitable material injection-molded behind it,which constitutes the main body of the present display unit,

FIG. 6 shows a section through a mold in which the main body inaccordance with FIG. 5 can be produced,

FIG. 7 shows a section through a detail from that region of the displayunit in accordance with FIGS. 1 and 2 where contact points are situated,

FIG. 8 shows a section through a detail from one of the edge regions ofthe display unit in accordance with FIGS. 1 and 2 where the contactpoints may likewise be situated,

FIG. 9 shows a section through the accommodation of a supply source inthe interior of the main body of the present display, and

FIG. 10 shows a vertical section through a curved part of the presentdisplay.

FIG. 1 shows a plan view of the front side of one of the possibleembodiments of the present three-dimensional electroluminescent display.This three-dimensional electroluminescent display is also calledhereinafter for short.

FIG. 2 shows a vertical section through the display unit from FIG. 1.The display unit has an essentially areal main body 1 provided with anelectroluminescent device 20. This device 20 is essentially assigned tothe front area 103 of the main body 1 and it can permit desiredgraphical representations such as images, numbers, etc. to appear toluminesce. Said main body 1 is made of a suitable plastic, it beingadvantageous if said plastic can be processed in an injection-moldingprocess. A material from the group of acrylonitrile butadiene styreneterpolymers (ABS) may be involved, by way of example.

A depression 101 having a circular contour is embodied in the front side103 of the main body 1 of the display unit illustrated. Said depression101 has a circularly peripheral side wall 102, the inner area of whichis practically at right angles to the main plane or to the front side103 of the areal main body 1. The surface of this portion of the innerarea 102 of the depression 101 adjoins the front area 103 of the mainbody 1. The peripheral side wall 102 thus projects downward and backwardfrom the front wall 103 of the areal main body 1. FIG. 2 furthermorereveals that a portion 201 of the electroluminescent device 20 continuesin the interior of the main body depression 101 and covers a part of theinner area of the wall 102 bounding the depression 101.

The depression 101 furthermore comprises a bottom 105, which, in theexample illustrated, is situated approximately at half the height of theperipheral side wall 102 of the depression 101. An opening 106 is madein the center of said bottom 105, through which opening, by way ofexample, the spindle of a potentiometer (not illustrated) can pass. Anactuating knob may be fitted to the protruding end of the spindle of thepotentiometer. The widening track 107 (FIG. 1), which practically runsparallel to the depression wall 102, indicates the direction in whichthe controlled variable, for example volume, acquires its larger value.

A cavity 7 is made in a further region of the main body 1 of the unit,which cavity opens toward the rear or backward. Said cavity 7 may have aquadrangular contour. In this case, said cavity 7 is laterally boundedby four walls 43 projecting backward from the rear side of the arealportion 103 of the main body 1. The cavity 7 serves for receiving asource 15 for supplying the electroluminescent device 20 with electricalenergy. The cavity 7 lies below said depression 101 in the case shown inFIG. 2. FIG. 2 also illustrates contact pins 17 and 18, via which a DCvoltage of 12 volts, for example, is fed to the source 15. Said contactpins 17 and 18 are situated at that side of the source 15 which isremote from the electroluminescent device 20.

FIG. 3 shows a vertical section through the structure of theelectroluminescent device 20, in which case FIG. 3 involves only aportion or detail from the device 20 which is illustrated in FIG. 2. Theelectroluminescent device 20 comprises a front transparent or at leasttranslucent and areal part 2, which is illustrated at the very top inFIG. 3. The film 2 must furthermore have the property of being able tobe thermoformed. Plastics which are suitable for producing such films 2are generally known. By way of example, a film marketed under the trademark Makrofol® by the company Bayer AG may be mentioned asrepresentative of other materials of this type as well. In order toobtain particular effects, the film 2 may also be realized by means ofmultilayer construction.

The underside or rear side of the film 2 illustrated in FIG. 3 isprovided with a two-dimensional motif 9. Said motif 9 may be, by way ofexample, three-dimensional graphical representations such as symbols,images, numbers, etc. The contents of such motifs 9 are defined bydiscrete elements 8 lying next to one another at intervals andintervening windows 81. Light which passes through the windows 81between the motif elements 8 to the film 2 reproduces the content of themotif 9. In the sectional illustration of FIG. 3, the motif elements 8appear as discrete lines provided on the back or rear side of the film2. Consequently, these motifs 9 are situated in the interior of theelectroluminescent device 20, where they are protected against abrasionand other adverse influences, for example, by the film 2 arranged infront of them.

The rear side of the film 2 and thus also the rear side of the motif 9is assigned the actual luminescent apparatus 10, which is anelectroluminescent apparatus in the case illustrated. This apparatus isalso called just EL apparatus or EL lamp 10 hereinafter. The ELapparatus 10 has two areal electrodes, namely a front electrode 11 and aback electrode 12, which are situated at a distance from one another. Adielectric 13 is arranged between said electrodes 11 and 12. Saiddielectric 13 is such that it can luminesce if the operating voltage isapplied to the electrodes 11 and 12 of the EL apparatus 10. A coveringlayer 14 made of an insulating material is deposited at the rear side ofthe EL apparatus 10.

During the production of the present unit, firstly theelectroluminescent device 20 is produced. In a first production step,the film 2 is provided. This means that the film 2 is initially presentin its undeformed, i.e. practically planar form. Said film 2subsequently serves as a carrier in the EL device 20, to be preciseinter alia also as a carrier for the EL apparatus 10. The rear or backside of the film 2 is provided with one or more motifs 9, for example byprinting. In a further production step, the first electrode, i.e. thefront electrode 11, of the EL apparatus 10 is provided on the rear sideof the motif 9 and on those regions of the rear side of the film 2 whichare uncovered between the motif elements 8. This may likewise be done ina method known per se. When choosing this method, care must be taken toensure that the front electrode 11 adheres on the film 2 as well aspossible. Furthermore, the material of the front electrode 11 must benot only conductive but also transparent or at least translucent. Thematerial of the front electrode 11 may be an inorganically ororganically based electrically conductive material, e.g. Baytron® and/orpolyaniline and/or polypyrrole, modified with highly flexible binders,e.g. based on PU, PMMA, PVA.

A further layer 13 is applied to said front electrode 11, said furtherlayer comprising the dielectric material already mentioned. Saidmaterial may comprise for example a mixture of ZnS, BaTiO₃ and thehighly flexible binders mentioned.

Finally, the third layer is deposited on the free, i.e. rear, surface ofsaid dielectric layer 13, which said layer constitutes the backelectrode 12. The material of said back electrode 12 may be aninorganically or organically based electrically conductive material,e.g. Baytron® and/or polyaniline and/or polypyrrole, modified withhighly flexible binders, e.g. based on PU, PMMA, PVA. In order toimprove the electrical conductivity, the material of said layer 12 mayhave silver or carbon added to it and/or be supplemented with a layermade of these materials.

Finally, the covering layer 14 is applied to the rear side of the ELapparatus 10.

Owing to the subsequent treatment of this electroluminescent device 20,it is extremely important that the individual layers of theelectroluminescent apparatus 10 also adhere on one another as well aspossible. The above-described composition of the individual layers 11 to14 ensures not only the immovable adhesion of said layers on one anotherbut also an expansibility of said layers that could not be achievedheretofore.

The electroluminescent device 20, in which the EL apparatus 10 adheresfixedly on the film 2, is now thermoformed, embossed, hollow-embossed,solid-embossed or the like (FIGS. 2 and 4). The electroluminescentdevice 20 which is formed in this way may also have, inter alia,elevations 3 and depressions 4 (FIG. 2). The thickness of these portions3 and 4 of the EL device 20 is essentially the same as the thickness ofthe nondeformed portions 5 (FIG. 2) of the electroluminescent device 20.

During said deformation of the electroluminescent device 20, it is evenpossible to obtain perforations in the electroluminescent device 20without this adversely affecting the functionality of theelectroluminescent device 20. FIG. 4 shows one of the regions of the ELdevice 20 in a vertical section which has such a perforation 110. Saidperforation 110 has a circular contour and said contour is adjoined byan extension 201 having the form of a short tubular piece. The wall 111or the walls of said extension 201 are at a practically right angle α tothe end face 29 of the electroluminescent device 20.

The extension 201 has been formed from that portion of the material ofthe EL device 20 which was situated within said circular contour of theperforation 110 and which was drawn into the perforation 110 by thethermoforming. A curved transition portion 6 (FIGS. 4 and 10) of the ELdevice 20 is situated between the extension 201 and the planar portionof the EL device 20 which surrounds the perforation 110. The radius ofcurvature of said transition portion 6, which extends from the end face29 of the electroluminescent device 20 as far as the side area 111 ofsaid extension 201, can be kept very small. By virtue inter alia of theimmovable adhesion of the layers 2, 9 and 11 to 14 on one another andalso owing to the expansibility of said layers 2, 9, and 11 to 14 whichhas not been able to be achieved heretofore, the radius of curvature ofthe transition portion 6 may be less than 1 mm without cracks arising inthe layers of the EL device 20. Moreover the wall 111 of the extension201 may be at an angle α of practically 90 degrees, i.e. practicallyperpendicular, to the end face 29 of the electroluminescent device 20.

The dielectric 13 constitutes a comparatively thick layer in comparisonwith the electrodes 11 and 12 of the EL device 20.

This dielectric layer 13 may comprise a plurality of layers lying one ontop of the other. The relevant portion of the transition region 6 of theEL device 20 is shown greatly enlarged in FIG. 10.

The electroluminescent device 20 illustrated in FIG. 10 has a dielectriclayer 13 comprising three layers 131, 132 and 133. Said layers 131, 132and 133 may be made of one of the abovementioned dielectric materials orthey may be made of different dielectric materials. During theproduction of the EL device 20, the layers 131, 132 and 133 are appliedindividually and successively to the front electrode 11 and to therespective layer applied previously.

The bottom edge 115 of the extension 201 is free. Owing to theextraordinary adhesion of the individual layers of theelectroluminescent device 20 on one another, as already mentioned, andowing to the high expansibility thereof, the electroluminescent device20 retains its original structure, or structure present in the region ofthe front area 103, in the thermoformed portion 201 as well.Consequently, the cylindrical inner area 111 of said extension 201 canalso radiate the light generated by the electroluminescent apparatus 10.

In this embodiment of the present invention it is possible to configurethe free end part 115 of the extension 201 in such a way that theelectrodes 11 and 12 do not reach as far as the cut edge 115. Both thefront electrode 11 and the back electrode 12 end at a distance from thecut edge 115. By contrast, both the covering layer 14 and the dielectriclayer 13 reach right into the region of the cut edge 115. This alsoentails, inter alia, a safety-relevant advantage, namely that theelectrodes 11 and 12, which are at a comparatively high electricalpotential, cannot be touched because their free edges are covered atleast by the insulating material of the covering layer 14. Moreover, thelayers 13 and 14 reaching as far as the cut edge 115 prevent possiblepenetration of moisture into the spaces between the individual layers ofthe electroluminescent device 20.

After thermoforming, the main body 1 is assigned to the rear side of theelectroluminescent device 20. This may be for example by a materialsuitable for this being injection-molded behind the electroluminescentdevice 20. Some of the materials suitable for this have already beenmentioned above. FIG. 5 shows a vertical section through that detailfrom the unit in accordance with FIG. 2 in which the depression issituated, to be precise together with the relevant portion of the mainbody 1 in which the extension 201 in the form of a tubular piece islocated. It is understood that the material of the main part 1 settleson the outer side of the extension 115 whilst being injection-moldedbehind.

FIG. 6 shows a mold 30, in which the unit shown in FIGS. 1 and 2 can beproduced by injection-molding behind the electroluminescent device 20.Said mold 30 has a lower part 31 and an upper part 32, which match oneanother and which are guided such that, by way of example, they can bepivoted or they can be displaced rectilinearly with respect to oneanother in a manner known per se when said mold 30 is to be opened andclosed. A first die insert 33 is situated in the lower part 31 of themold and a second die insert 34 is situated in the upper part 32 of themold. The course of the surface of the cavity in the respective dieinsert 33 or 34 corresponds to the course of the desired surface of thatside of the display unit which is to be molded by the relevant dieinsert 33 or 34. Channels 37 are made in the lower part 31 of the mold,through which channels the material which is to pass into the cavity ofthe mold is introduced into the mold 30 and distributed therein.

The course of the surfaces of the film 2 has already been described inconnection with FIG. 2. The course of the surface of the cavity in theupper die insert 34 must correspond to the course of the outer surfaceor the front area of the film 2. The same applies correspondingly to theform of the surface of the cavity in the lower die insert 33. Hereattention should primarily be drawn to two projections 38 and 39 whichare situated at a distance from one another and project from the surfaceof the cavity in the lower die insert 33. The height of said projections38 and 39 is chosen in such a way that the end face of said projections38 and 39 bear on the rear side of the EL device 20 during the processof injection-molding behind. As a result, two channels 38 and 39 remainfree in this region of the main body 1, the use of said channels beingdescribed below.

The supply source 15 already mentioned includes an electronic part,namely a converter 16, which converts a comparatively low DC voltage of12 V, for example, into a comparatively high AC voltage required for theoperation of the EL apparatus 10. In the case illustrated, saidconverter 16 is incorporated in the cavity 7 of the main body 1 alreadymentioned and held in place with the aid of a clamping sleeve 44, forexample. Otherwise, the converter 16 may be incorporated only partiallyin the main body 1 of the display unit or it may be present as a unitindependent of the display unit.

The contact pins 17 and 18, likewise already mentioned, project from therear side of the converter 16, and may partially project from thematerial of the main body 1. The poles of a DC voltage source, e.g. ofan accumulator (not illustrated), may be connected to the portions ofthe pins 17 and 18 projecting from the main body 1. The voltage requiredfor the operation of the electroluminescent device 20 may be 110 V/400Hz and it is connected to the electroluminescent device 20 via contactapparatuses 21 and 22. (FIGS. 7, 8 and 9).

The first of said contact apparatuses 21 makes contact with the backelectrode 12 of the EL lamp 10. The second of the contact apparatuses 22makes contact with the front electrode 11 of the EL lamp 10. The firstof said contact apparatuses 21 lies in the first channel 38 of the mainpart 1. The second of the contact apparatuses 22 lies in the secondchannel 39 of the main part 1. The respective contact apparatus 21 or 22comprises a spring, a helical spring 210 or 220, respectively, in thecase illustrated. The springs 210 and 220 bear at one end on acorresponding electrically conductive output point 211 and 221,respectively, of the converter 16. The other end of the spring 210 ofthe first contact apparatus 21 bears on the material of the backelectrode 12 of the EL apparatus 10. The other end of the spring 220 ofthe second contact apparatus 22 bears on the material of the frontelectrode 11 of the EL apparatus 10.

The arrangement illustrated in FIG. 7 relates to the case, if thecontact apparatuses 21 and 22 are assigned to a region of the EL lamp 10of this, where the electrodes 11 and 12 of the EL lamp 10 do not lieabove one another. This may be the case for example in an edge part 42of the EL lamp 10, which is represented in FIG. 7. In said edge part 42,the marginal edge of the back electrode 12 is at a greater distance fromthe edge 42 of the EL lamp 10 than the marginal edge of the frontelectrode 11. Only the covering electrode 14 reaches as far as the edge42 of the EL lamp 10, said electrode being made of an electricallyinsulating material.

If contact is to be made with the electrodes 11 and 12 of the EL lamp 10by the supply source 15 in an inner region of the EL lamp 10 in whichthe electrodes 11 and 12 lie one above the other, then an opening 43 forthe passage of that contact apparatus 22 which is to make contact withthe front electrode 11 has to be made in the layer of the back electrode12. The opening 43 in the back electrode 12 must be large enough thatsaid contact apparatus 22 does not make contact with the back electrode12. For this purpose, it normally suffices if the opening 43 in the backelectrode 12 is large enough to prevent the spring 220 of the contactapparatus 22 for the front electrode 11 from making contact with theback electrode 12.

After the main part 1 of the display unit has been produced byinjection-molding behind the electroluminescent device 20, theelectroluminescent device 20 adheres on the main body 1. The supplysource 15 mentioned is then inserted into the cavity 7 of the main body1, to be precise in such a way that the contact apparatuses 21 and 22lie in the channels 38 and 39 of the main body 1. The supply source 16is then pressed into the cavity 7 until the front ends of the springs210 and 220 bear on the conductive layer of the relevant electrode 12and 13, respectively, of the electroluminescent apparatus 10. Afterward,the supply source 15 has to be fixed in this position, which may be donefor example by means of a suitable adhesive or the like.

FIG. 8 shows a further possibility in respect of how the supply source15 can be assigned to the main body 1. In this case, the substantialpart of the supply source 15 is incorporated in the main body 1. Inorder to produce this arrangement, an areal adapter piece 46 is used. Insaid adapter piece 46, there are channels 48 and 49 extendingperpendicular to the main areas of the adapter piece 46. One of thelarge areas of the adapter piece 46 is adhesively bonded on the coveringlayer 14 of the EL lamp 10. The supply source 15 is then assigned to theadapter piece 46 in such a way that the respective spring 38 or 39 ofthe supply source 15 passes through one of the channels 48 or 49,respectively, in such a way that its front end bears on the relevantelectrode 11 or 12, respectively, of the EL lamp 10. The front side ofthe converter 16 is adhesively bonded onto the large area of the adapterpiece 46 which is remote from the EL lamp 10. The semifinished productthus prepared may be inserted into the mold 30 and have the material ofthe main body 1 injection-molded behind it. In this case, the lower part31 of the mold 30 is shaped such that the material of the main body 1 isalso situated behind the converter 16, and that only portions of thepins 17 and 18 to which the DC voltage already mentioned can be appliedproject from said material of the main body 1.

The display unit comprises the main body 1 and the EL device 20. Saidelectroluminescent device 20 comprises the film 2 and theelectroluminescent apparatus 10, which together form a whole. That areaof the film 2 which faces the electroluminescent apparatus 10 isprovided with motifs 9 to be displayed. The electroluminescent apparatus10 comprises the front electrode 11 and the back electrode 12, betweenwhich the dielectric 13 is situated. The front electrode 11 is assignedto the layer that reproduces the motif 9, and is in one piece with saidlayer. The supply source 15, which makes contact with the electrodes 11and 12 of the electroluminescent device 20, is arranged within the areaof the electroluminescent device 20.

1. A three-dimensional electroluminescent display having a transparentfront part (2) and having an electroluminescent apparatus (10) arrangedbehind the front part, characterized in that at least the layers of theelectroluminescent device (20) are fixedly interconnected in such a waythat these layers withstand even a high degree of curvature of theelectroluminescent apparatus (10) without damage.
 2. The display asclaimed in patent claim 1, characterized in that the electroluminescentapparatus (10) has two areal electrodes (11, 12) situated at a distancefrom one another, in that a dielectric (13) is situated between theelectrodes (11, 12), in that said dielectric is such that it can effectluminescence if a voltage is applied to the electrodes.
 3. The displayas claimed in patent claim 1, characterized in that the front part (2)is embodied as a film, in that the motif (9) is applied on the back orrear large area of the film (2), and in that the front electrode (11) ofthe electroluminescent apparatus (10) is applied on the motif layer (9).4. The display as claimed in patent claim 2, characterized in that theouter large area of the back electrode (12) of the electroluminescentapparatus (10) is provided with a covering layer (14).
 5. The display asclaimed in patent claim 1, characterized in that a main body (1) isassigned to the outer large area of the electroluminescent device (20).6. The display as claimed in patent claim 5, characterized in that themain body (1) is provided with at least one depression, in that saiddepression has at least one side wall which is practically perpendicularto the front area of the main body (1), and in that theelectroluminescent apparatus (10) assigned to the front wall of the mainbody (1) continues with a corresponding portion in the depression, andin that said portion of the electroluminescent apparatus (10) bears onthe side wall of the depression.
 7. The display as claimed in patentclaim 1, characterized in that a converter (16) is provided, which canconvert a DC voltage into an AC voltage, in that the output of saidconverter is connected to the electroluminescent apparatus (10), and inthat the converter (16) may be incorporated at least partially in thematerial of the main body (1) of the display unit.
 8. A method forproducing the display as claimed in patent claim 1, characterized inthat an essentially planar film (2) is provided, in that one of thelarge areas of said film is provided with a motif (9), and in that theelectroluminescent apparatus (10) is assigned to the film (2) in such away that the front electrode (11) of said electroluminescent device (20)lies on that side of the film (2) which is provided with the motif (9).9. The method as claimed in patent claim 8, characterized in that theelectroluminescent device (20) is thermoformed.
 10. The method asclaimed in patent claim 9, characterized in that the thermoformedelectroluminescent device (20) has a plastic injection-molded behind it.